1. Field of the Disclosure
Embodiments of the present disclosure relate generally to thrust reversers for turbine engines, and more specifically to cascade elements for thrust reverser configured to provide improved reverse thrust and reduced noise.
2. Background of Related Art
Commercial aircraft fly at very high speeds and can be extremely heavy. A fully loaded Boeing 747-400, for example, has a cruise speed of approximately 565 mph and a maximum take-off weight of approximately 833,000 lbs. As a result, the wings are optimized for efficient cruising, with some tradeoff on take-off and landing speeds. 747-400 approach speeds vary between approximately 150-180 mph, depending on payload, temperature, humidity, etc.
Obviously, stopping several hundred thousand pounds from these speeds requires a great deal of braking force. A portion of this energy is absorbed by the braking system and converted to heat, which is then dissipated using ducts and vents. Relying completely on the braking system, however, placed undue stress on the brake rotors and pads, the landing gear, and the tires. As a result, many modern aircraft, including the 747-400, also use thrust reversers.
As the name implies, thrust reversers reverse the thrust from the engine to create braking force. This can shorten landing field length, or the distance within which the plane can safely land, significantly and can reduce brake and tire wear. Thrust reversers can also reduce wear and tear on the landing gear, reducing maintenance, because a portion of the energy required for stopping the aircraft is provided by the engines rather than being transmitted through the landing gear.
A problem with conventional thrust reversers, however, is that they tend to be very loud. This restricts their use to daytime only, for example, in some areas. The blasting, or broadband, noise cause by the reversers can alarm passengers and disturb local residents and wildlife, among other things. In addition, conventional thrust reversers are not particularly efficient at providing reverse thrust (e.g., on the order of 40-45% efficient).
What is needed, therefore, is a thrust reverser system that incorporates features designed to increase the reverse thrust provided by the system, while lowering the noise created thereby. The system should reduce the weight of the system and be cost effective using currently available manufacturing techniques. It is to such a thrust reverser system that embodiments of the present disclosure are primarily directed.